Cam-type tongs



Oct. 12, 1965 J. DURANEL GAM-TYPE TONGS Filed Jan. 15, 1964 United States Patent Office 3,211,488 Patented Oct. 12, 1965 3,211,488 CAM-TYPE TONGS Jean Duranel, Vaucresson, France, assignor to Ethylene- Plastique, Paris, Seine, France, a French society Filed Jan. 15, 1964, Ser. No. 337,832

Claims priority, application France, Jan. 17, 1963,

Claims. (Cl. 294-16) This invention is concerned with cam-type tongs.

The very large number of types of tongs at present available are provided with various means for closing the tongs, such closure means most commonly comprising a metal spring. rIlhis has a certain number of disadvantages; thus the metal spring is an additional part which has to be inserted, metal springs are expensive and they become damaged in the course of time. They oxidise, their springiness is not constant and they ultimately break.

An object of the present invention is to provide camtype tongs which reduce or avoid these disadvantages.

Cam-type tongs according to the invention comprise two arms connected by a pivot about which the arms can pivot, and a cam which is slidable perpendicularly to the pivot and which bears on a track provided on one of the two arms, the cam in one of the two end positions of its sliding movement enabling one of the arms to pivot wit-h respect to the other about the pivot and in the other serving to lock the two arms in the closed position of the tongs.

A pair of tongs according to the invention does not include a metal spring and when one or more components of the tongs are made of a plastic material, they can be made by moulding. The tongs include only a small number of components, namely, the two arms, the pivot and the sliding cam; the pivot may be borne by one of the two arms.

In a preferred embodiment of the invention, the track against which the sliding cam bears is formed by a part of one arm which can be deformed by moving away from the main body of the arm, thus providing a certain elasticity for the tongs in the closed position.

The sliding cam advantageously has a push member disposed perpendicularly to the direction of cam travel and enabling the cam to be easily located in either of the two positions required.

A preferred embodiment of a pair of tongs according to the invention will now be described, by way of example only, with reference to t-he accompanying drawings in which:

FIGURE 1 is a longitudinal section of the pair of tongs;

FIGURE 2 is a section on the line II-II in FIG- URE 1;

FIGURE 3 is a longitudinal section in the open position;

FIGURE 4 is a longitudinal section in the closed position;

FIGURE 5 is a longitudinal section in the closed position under an extension force.

The illustrated embodiment is intended particularly for use with fruit buds as described in French Patent No. 1,245,981, but it will be apparent that cam-type tongs according to the invention can be used for other purposes, the jaws of the tongs being adapted according to the required use.

Referring to the drawings, the tongs comprise two arms 1 and 2 which are connected by a pivot 3 which, as will be apparent from FIGURE 2, engages in the outer plates 4 and 5 of the arm 2 and the inner plates 6 and 7 of the arm 1.

In an alternative embodiment, each plate 6 and 7 of the arm 1 is provided with a half-pivot and in this embodiment, the assembly formed by the half-pivots of t-he plates 6 and 7 and the arm 1 may be made from one material by moulding.

A cam 8 is disposed between the plates 6 and 7 of the arm 1, the pivot 3 engaging in slots 9 and 10 formed in the walls 11 and 12 of the cam, these walls preferably being braced, see FIGURE 2.

The tongs can be very rapidly assembled since it is only necessary to put t-he plates 6 and 7 of arm 1 in place inside the plates 4 and 5 of arm 2, and then position the cam 8 so that the slots 9 and 10 register with apertures formed in the plates 4, 6, 7 and 5. The pivot 3 is then fitted in the various aligned apertures so as to complete the assembly.

T-he pivot 3 advantageously has at least one shoulder, e.g., 13, so that once the pivot has been force-fitted it remains in position without any danger of working loose.

Cam 8 is provided with a push member 14 parallel to the pivot 3 for ease of manipulation of the cam.

In `the drawing it will be seen that the ends of the two arms 1 and 2 have chambers 15 and 16 to receive a bud as explained in the above-mentioned French patent, at least one of the two chambers advantageously being provided with a pad of expanded plastic material.

The arm 2 includes a track 17 against which the cam 8 bears, the track being separated from the two edges of the arm 2 and being connected thereto only by one of its four sides. The track 17 thus acts as a resilient strip, as will be explained below:

In FIGURES Il and 3, the cam 8 is in one of its two end positions, namely the position which enables the tongs to be opened. In the position shown -in FIGURE l, it is only necessary to exert a slight pressure, as shown by the arrows in FIGURE 3, on the ends of the two arms remote from the chambers 15 and 16 to open the tongs. The tongs can be opened with a larger opening angle than shown in FIGURE 3, until the ends of the two arms 1 and 2 corne into contact, this angle preferably being at least equal to 45 To close the tongs pressure is applied to the push member 14 to move the cam away from the chambers 15 and 16 as shown in FIGURE 4. The bottom part of the cam, which preferably has a rounded shape as shown in the figures, is thus moved over the track l17 and during this movement the two arms 1 and 2 pivot about the pivot 3 so as to close the tongs.

A lug 18 is advantageously provided at the end of the arm 1 to serve as an abutment for the cam 8 when it is in the closed position and prevent the cam from lifting in that position (FIGURE 4).

When a bud is disposed inside the chambers 15 and 16, which are preferably provided with a pad of expanded material, the two arms of the tongs may open very slightly because of the possibility of deformation of the track 17 as shown in FIGURE 5; it will be seen from this ligure that the track 17 is slightly depressed in relation to the position shown in FIGURE 4 as a result of the bud expansion thrust shown by the arrows in the chambers 15 and 16 in FIGURE 5.

In a pair of tongs according to the invention a constant pressure can thus be exerted according to the elasticity and the deformability of the track 1,7, such a pressure being uniformly distributed over the bud by means of the pad of expanded material.

A pair of tongs of the kind described hereinabove is advanta-geously made of a plastic material, such as a polyolen, for example polyethylene, because the parts making up the tongs can be moulded without diiculty and assembled very rapidly. Moreover, the absence of any metal part gives the tongs constant properties and, since the tongs are locked in the closed position by means of a movable cam, no force is required to open the tongs, since it is only necessary to move the cam as shown in FIGURE 4, towards the front of the tongs, to open the latter. There is therefore no need-as is the case with conventional tongs-to overcome the pressure of a spring to open the tongs, the application of which pressure rapidly becoming difficult when it has to be repeated very frequently.

Iclaim:

1. Cam-type tongs comprising two arms, pivot means connecting said two arms for relative angular movement about a transverse axis between an open position of the tongs and a closed position of the tongs, and a cam member having at least one elongated slot receiving said pivot means so as to be movable at right an-gles to said axis along one of said arms between two extreme locations, the other of said arms having a portion defining a track against which said cam member slidably bears to hold said arms against relative angular movement from said closed position of the tongs when said cam member is in one of said extreme locations and to free said arms for relative angular movement to said open position of the tongs when said cam member is in the other of said extreme locations.

2. Cam-type tongs as in claim 1; wherein said track defining portion of the other arm is resiliently joined to the remainder of the latter so that, when said cam member is in Vsaid one extreme location, said track defining portion can resiliently deflect relative to said remainder of said other arm and thereby permit slight opening of the tongs against a yieldable force tending to hold the tongs in said closed position.

3. `Cam-type tongs as in claim 1; wherein said cam member has a push element projecting therefrom at right angles to the direction of the movement of the cam member along said one arm so that said push element can be easily manipulated for disposing the cam element in either of said extreme locations.

4. Cam-type tongs comprising two arms, pivot means extending transversely between said arms and connecting the latter for relative angular movement about the axis of said pivot means between an open position of the tongs and a closed position of the tongs, anda cam member having at least one elongated slot receiving said pivot means so as to be movable at right angles to said axis along one of said arms'between two extreme locations, the other of said arms having a portion defining a track facing toward said one arm and against which said cam member slidably bears, said cam member being shaped to present to said track ya cam portion spaced substantially from said axis to hold said arms against relative angular movement from said closed position of the tongs when said cam member is at one of said extreme locations and to present to said track a cam portion which is relatively close to said axis to free said arms for large relative angular movement lto said open position of the tongs when said cam member is at the other of said extreme locations.

5. Camtype tongs as in claim `4; wherein said track defining portion of the other arm is resiliently joined to the remainder of the latter so that, when said cam member is in said one extreme location, said track dening portion can resiliently deflect relative to said remainder of said other arm and thereby permit slight opening of the tongs against a yieldable force tending to hold the tongs in said closed position.

References Cited by the Examiner UNITED STATES PATENTS 573,036 12/96 IPiaget 81--43 1,108,299 y8/14 WSman v ....f 81-43 HUGO O. SCHULZ, Primary Examiner.

SAMUEL F. COLEMAN, Examiner. 

1. CAM-TYPE TONGS COMPRISING TWO ARMS, PIVOT MEANS CONNECTING SAID TWO ARMS FOR RELATIVE ANGULAR MOVEMENT ABOUT A TRANSVERSE AXIS BETWEEN AN OPEN POSITION OF THE TONGS AND A CLOSED POSITION OF THE TONGS, AND A CAM MEMBER HAVING AT LEAST ONE ELONGATED SLOT RECEIVING SAID PIVOT MEANS SO AS TO BE MOVABLE AT RIGHT ANGLES TO SAID AXIS ALONG ONE OF SAID ARMS BETWEEN TWO EXTREME LOCATIONS, THE OTHER OF SAID ARMS HAVING A PORTION DEFINING A TRACK AGAINST WHICH SAID CAM MEMBER SLIDABLY BEARS TO HOLD SAID ARMS AGAINST RELATIVE ANGULAR MOVEMENT FROM SAID CLOSED POSITION OF THE TONGS WHEN SAID CAM MEMBER IS IN ONE OF SAID EXTREME LOCATIONS AND TO FREE SAID ARMS FOR RELATIVE ANGULAR MOVEMENT TO SAID OPEN POSITION OF THE TONGS WHEN SAID CAM MEMBER IS IN THE OTHER OF SAID EXTREME LOCATIONS. 